1. Field of the Invention
The present invention relates to measuring apparatus in general and, more particularly, to consistometers.
2. Description of the Prior Art
Consistometers, heretofore of the type disclosed in U.S. Pat. No. 3,812,706, which issued on May 28, 1974 and is assigned to Texaco Inc., assignee of the present invention, provided a graphical record of the consistency of material being measured. As problems developed in that type of consistometer, the problems would not be detected until an operator visually viewed the measured consistency and determined that there was something erroneous in the record. There may exist a substantial time lag between the occurrence of a malfunction and the notice of that malfunction by an operator.
Similarly, the consistometer of the type disclosed in U.S. Pat. No. 3,668,677, which issued on June 6, 1972 and is assigned to Texaco Inc., assignee of the present invention, provided an alarm when spurious signals occur instead of valid signals. Malfunctions can occur where there is no spurious signal and cannot be detected in the graphical recording. The present invention provides for indication to an operator of normal operation until a malfunction occurs either in the sensing of the rotation of the reference member or resilient member during the measuring process or a misalignment of the resilient member and the reference member during their rotation.
Further, misalignment detection is helpful in the installation and setting up of the consistometer and for the periodic schedule maintenance that is normally required on consistometers.